I have a 500 mile rule, if it is less than 500 miles, I drive. Over 500, I fly. There are exceptions, of course, but here is the math for 500 miles.

I live rural, near an interstate highway. So if where I am going is 500 miles, I am looking at 8-10 hours allowing for stops for fuel, food and just to walk around.

I live 1.5 hours from the nearest airport. I allow 1.5 hours for clearing parking, check-in and security. It is a smaller regional airport, so this is adequate. New math has me adding 30 minutes for the new procedures, but this may not be necessary long term. Total so far: 3.5 hours.

500 mile flight: 1.5 hours gate to gate. 5 hours total.

Wait for luggage (I have to check a bag) plus get rental car, plus get on road. 1 hour usually unless it is an exception airport. 6 hours now.

My final destination is generally less than one hour to the airport, so call it 1 hour with traffic. Total 7 hours. I take into account the risk of lost luggage, airport delays, and this turns into roughly the same, on the outbound, but it slightly favors flying.

The return is where the math works in my favor. If I can coordinate my work being done just as I need to go to the airport, then then return math works exactly like the outbound math. But, we all know this does not happen. Many of us schedule the first flight out of the morning after the work is over. If I am driving, as soon as the job is done I start home. It may be 12 hours before the first flight leaves, and I may have to pay a significant premium to be on it. It may be sold out.

So the lost time occurs mostly on the return. The beauty in driving is starting home at the earliest possible time.

It might also be less expensive on your employer to drive, but I do not find the difference to be hugely significant at current mileage reimbursement rates, but it can be.

There are two down sides, the loss of productivity while driving. I do get some work done while at the hotel and airport. And weather. It is much easier to fly over winter storms than through them.

Because of the new potential for added delay, I am currently considering a 600 mile rule, but the extra two hours on the road may be just a bit too exhausting. I may need a better car.